Elevator brake



F 1930- w. G. TURNBULL ET AL ELEVATOR BRAKE Filed March 16. 1926Inventors Will/am G. Tar/76. Ham/d 6'. Chime.

' Patented- Feb; 11', 1930 PATENT OFFICEU' WILLIAM eoimon 'rUmuLL ANDHAROLD CBEIGHTON CRANE, OI TORONTO ONTARIO, CANADA.

- ELEVATOR BRAKE Application flied March 16,1926. Serial in. 95,152. A

The princi al' object of this invention is, to increase t e operatinefliciency of high speed elevators by provi ing means separate from-thearresting and holding brake which Y will effectively slowdown themovement of the elevator car to the ordinary brake.

The principal feature of the invention consists in the arrangement inconnection with an elevator driving mechanism, of a supplementarybraking device which will appl the maximumtorque to the driving shatwhen the elevator is in motion and gradually 1 reduce the torque as thespeed of the mechanism decreases.

In the drawin s, Figure 1 is a plan view of an elevator riving unitequipped with our improved brakin device.

Figure 2 is a side e evational view in part mid-section.

' Figure 3 is a transverse section on the line 3--3 of Figure 1 showinga portion of the hydraulic brake casing broken away. 5' In the operationof electrically driven high speed elevators with a single speed drive,the ordinary friction brake is subjected to very heavy stresses andit'is diflicult to efi'ect accurate landin s.

This invention has been devised to relieve the stress on the ordinarybraking apparatus by exerting a retarding torque which will effectively.slow down the operation of the mechanism prior to the application of thestopping brake thus effecting a positive low speed from which accuratelandings with smooth stops may be made.

In'the accompanying drawings, the assembly illustrated is that of astandard type 40 of drive having the cable sheave 1 operated by a'wormon the motor shaft 2.

A standard friction brake 3 is applied to the motor shaft, beingelectrically governed from the control mechanism in the car in the usualmanner.

The supplementary brake herein illustrated consists of a drum 4rotatably mounted upon the shaft? and enclosing a rotor memher 5 whichis keyed to the motor shaft.

The rotor is provided with a plurality of facilitate the making ofaccurate landings and reduce the stress on;

radial arms 6 preferably arranged in pairs and between these arms arearranged a plurality of radial arms 7 secured to and extending inwardlyfrom the drum 4.

The periphery of the drum' 4 rotates between the brake shoes 8..whichare of the same type as applied to-the brake 3.

This drum 4 is filled with oil or. other suitable fluid and when thebrake shoes-8 are out of engagement with the drum 4, said drum rotateswith the rotor and the shaft.

Immediately upon the application of the brakes 8 to grip the drum 4 andretard its rotation a resistance ensues' between the radial arms 6 and 7through the fluid medium within the drum causing a reacting torquebetween the rotor and the drum which Varies in directrelation to theirrelative speed, de-

veloping the maximum torque at the maxii mum motor speed with the drumat. rest.

It will be understood of course that the construction of the rotor andthe enclosing drum may be varied, very considerably as may also variousother features of construction without departing from the essentialfeature of the invention.

When the elevator is being operated at high speed both the specialhydraulic brake herein described and the friction brake are released andthe drum-4 will acquire a speed so slightly less than the motor speed.The slip between the drum and rotor is just suflicient to develop torqueenoughto overcome bearing friction and windage of the member 4.

When it is desired to bring the elevator to a stop the shoes 8 of thebrake 4- are first applied and as soon as the drum is brought to restthe maximum kinetic energy of the moving mechanism is opposed to theresistancev of the drum with its impeding vanes retarding the movementof the fluid in the drum. The maximum torque is then developed and thespeed of the mechanism decreases. The retardation decreases until such aspeed is reached'that the torque developed between the rotor and thedrum is just suflicient to balance the net torque due to the motor andload. The arresting brake may be applied at any desirable period in theslowing down of the mechanism but by reason of the initial slow down thestop will be quite the rotor through the arresting of said latsmooth andas the stress on the arresting ter rotative member. brake is light anaccurate stop may be made. I 5. In an elevator brake, the combination\Vith a slow-down type of brake such as dewith the motor shaft driven inboth direc- U scribed, it is possible to operate the elevator tlons anda frlction brake thereon, of arotor Ma slow speed, such as for inchingat landfixed to the shaft and having radial vanes, ings.. To utilize thedevice in this manner a drum rotatably mounted on the shaft and theusual friction brake is released and power enclosing said rotor andbeing normally free is applied to the motor with the drum 4 to rotatetherewith in the same direction,

10 held from rotation. The ultimate speed of sald drum having radialvanes arranged adjathe motor and therefore the elevator is precent tothe radial vanes of the rotor, a fluid determined at a limited low valueby the remedium enclosed in said drum, and braking sistance of the fluidwithin the drum. means for arresting the drum against its nor- It willbe readily understood that a retardmal rotation with the shaft.

ing brake such as described will be extremely WILLIAM GORDON TURNBULL.

applicable to elevator control as the kinetic HAROLD CREIGHTON CRANE.

energy of the elevator movement varies as the square of the speed andthe'torque of the hydraulic brake also varies as the square 20 of thespeed. l

' What we claim as our invention is:

1. In an elevator brake, the combination with the means for driving anelevator operating mechanism in both directions and an 25 arrestingbrake therefor, of a supplementary brake applied to saidmechanism'adapted to develop a torque in either direction of rotationwhich diminishes as the speed of the elevator mechanism decreases.

so 2. In an elevator brake, the combination with the means for drivingan elevator 0 erating mechanism in both directions an an arresting braketherefor, of a mechanical- 'ly controlled fluid-impeded supplementary a5braking means adapted when controlled to automatically oppose themovement of said elevator operating mechanism in either direction withan intensity relative to the speed of travel ofsaid elevator tode-celerate the 40 same independent of the arresting brake.

3. In an elevator brake, the combination withthe elevatordrivingmechanism and a mechanical brake therefor, of a supplementarybrake member adapted to normally ro- 45 tate with said driving mechanismin either 11 direction, fluid means interposed between said drivingmeans and said supplementary brake member and normally eifecting adriving connection between the two to rotate the 50 supplementary brakemember With the driv- 116 ing means, and means for arresting the normalrotation of said supplementary ,brake member to effect a retardingaction on said driving mechanism through the fluid means interposedtherebetween.

4. In an elevator brake, the combination with the means for driving anelevator mechanism in both directions and an arresting 60 brake, of arotor operatively connected with the driving mechanism, a member adaptedto normally rotate freely with said rotor in either, direction, meansfor arresting the movement of the latter rotative member, and

65 means for eflectihg a retarding influence on

